CN114380592A

CN114380592A - Cherry-colored zirconia sintered body, cherry-colored zirconia powder, and method for producing cherry-colored zirconia powder

Info

Publication number: CN114380592A
Application number: CN202111163382.6A
Authority: CN
Inventors: 国贞泰一
Original assignee: Daiichi Kigenso Kagaku Kogyo Co Ltd
Current assignee: Daiichi Kigenso Kagaku Kogyo Co Ltd
Priority date: 2020-10-02
Filing date: 2021-09-30
Publication date: 2022-04-22
Anticipated expiration: 2041-09-30
Also published as: CN114380592B; JP2022059792A

Abstract

To provide a cherry-colored zirconia sintered body which has high strength even when produced under a low molding pressure, has a bright and vivid color, and has a good color balance. The cherry blossom-color-based zirconia sintered body comprises zirconia, yttria, erbium oxide, alumina, zinc oxide, and silica, wherein the content of yttria is 0.7 mol% or more and 1.5 mol% or less, the content of erbium oxide is 0.7 mol% or more and 1.5 mol% or less, the content of alumina is 0.1 mass% or more and 0.4 mass% or less, the content of zinc oxide is 0.2 mass% or more and 0.3 mass% or less, the content of silica is 0.05 mass% or more and 0.1 mass% or less, and the relative sintered density is 99.5% or more.

Description

Cherry-colored zirconia sintered body, cherry-colored zirconia powder, and method for producing cherry-colored zirconia powder

Technical Field

The present invention relates to a cherry-colored zirconia sintered body, a cherry-colored zirconia powder, and a method for producing the cherry-colored zirconia powder.

Background

The zirconia sintered body, particularly the tetragonal zirconia sintered body, has been gradually applied to household goods such as a cutter and sports goods such as a golf tee due to its high strength and beautiful surface gloss after mirror polishing, and its application is being expanded to decorative parts such as a watch case and accessories. In order to cope with such expansion of use, zirconia having various colors is strongly demanded. Among various colors, cherry-colored zirconia sintered bodies are in great demand.

Patent document 1 discloses a pink zirconia sintered body for ZrO containing a stabilizer₂0.5 to 2.0 mol% of Er₂O₃And 0.1 to 0.6 mol% of ZnO.

Patent document 2 discloses a pink zirconia sintered body containing 2 to 5 mol% of Y as a stabilizer₂O₃1 to 3 wt% of erbium oxide, and less than 0.5 wt% of Al₂O₃The brightness L in the L a b color system is 65-85, a is 0-10, b is 0-3.

Patent document 3 discloses a colored light-transmitting zirconia sintered body containing 2 to 4 mol% of yttria and 0.02 to 0.8 mol% of Er₂O₃With Fe₂O₃Less than 20 to 2000ppm of iron compound and less than 0.005 to 0.2 wt% of Al₂O₃The balance is zirconia, the brightness L of color parameters specified in JIS-Z8729 is 55-75, a is 0-10, b is 0-30, the relative density is 99.80% or more, and the total light transmittance of the D65 light source is 18% or more and 40% or less at a sample thickness of 1 mm.

Patent document 4 discloses a pink zirconia sintered body made of yttria (Y)₂O₃) And erbium oxide (Er)₂O₃) And further, 0.005 wt% or more and less than 0.2 wt% of alumina, 0.1 mol% or more and less than 2 mol% of erbium oxide, 1 mol% or more and less than 4 mol% of yttrium oxide, and the zirconia sintered body has a brightness L of 58 to 75, a of 3 to 20, and b of-8 to-4 in color parameters specified in JIS Z8729.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. H04-2658

Patent document 2: japanese patent laid-open publication No. 2011-20875

Patent document 3: japanese laid-open patent publication No. 2014-141388

Patent document 4: japanese laid-open patent publication No. 2014-141393

Disclosure of Invention

Problems to be solved by the invention

However, the conventional pink zirconia sintered body as described above cannot be said to be a zirconia sintered body having a good color balance. In addition, in the molding when obtaining a sintered compact of pink zirconia by using a powder of pink zirconia, it is usually necessary to use 2t/cm²The left and right molding pressures have a problem of high processing load.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a cherry blossom-colored zirconia sintered body which has high strength, bright and vivid color, and is excellent in color balance even when produced under a low molding pressure. Further, provided is a cherry-colored zirconia powder which can be easily produced from the sintered cherry-colored zirconia. Also provided is a method for producing the cherry blossom-color-based zirconia powder.

Means for solving the problems

The present inventors have intensively studied on zirconia sintered bodies. As a result, it has been surprisingly found that a cherry blossom-colored zirconia sintered body having high strength, a bright and vivid color and a good color balance can be obtained even at a low molding pressure by adopting the following structure, and the present invention has been completed.

That is, the cherry blossom-colored zirconia sintered body of the present invention includes:

zirconia, yttria, erbium oxide, alumina, zinc oxide, and silica;

the content of the yttrium oxide is 0.7 mol% or more and 1.5 mol% or less with respect to the zirconium oxide;

the content of erbium oxide is 0.7 mol% or more and 1.5 mol% or less with respect to the zirconia;

the content of the alumina is 0.1 mass% or more and 0.4 mass% or less, assuming that the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%;

a content of the zinc oxide is 0.2 mass% or more and 0.3 mass% or less, assuming that a total amount of the zirconium oxide, the yttrium oxide, and the erbium oxide is 100 mass%;

the content of the silica is 0.05 mass% or more and 0.1 mass% or less, where the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%;

the relative sintering density is more than 99.5 percent.

Yttria acts as a stabilizer in a manner that does not affect coloration. On the other hand, erbium oxide functions as a colorant of cherry flower color and also functions as a stabilizer. Alumina, zinc oxide and silica act as sintering aids, while increasing whiteness and brightness.

The cherry blossom-colored zirconia sintered body of the present invention contains yttria, erbium oxide, alumina, zinc oxide, and silica in the above numerical range, and therefore has high strength even when produced under a low molding pressure. Specifically, the cherry blossom-shaped zirconia sintered body of the present invention has a high strength because the relative sintered density is 99.5% or more. Further, since zirconia, alumina, zinc oxide and silica are contained in the above numerical ranges, the color filter has a bright and vivid color and a good color balance.

As described above, the cherry-colored zirconia sintered body of the present invention contains yttrium oxide, erbium oxide, aluminum oxide, zinc oxide, and silicon dioxide in the above numerical value ranges, and therefore has high strength, bright and vivid color tone, and good color balance even when produced under a low molding pressure. This can also be seen in the examples.

In the structure, it is preferable that the content of the yttria is 0.9 mol% or more and 1.3 mol% or less with respect to the zirconia;

the content of erbium oxide is 0.9 mol% or more and 1.3 mol% or less with respect to the zirconia;

the content of the alumina is more than 0.2 mass% and 0.4 mass% or less, assuming that the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%.

In the structure, it is preferable that the content of the yttria is 1.0 mol% or more and 1.2 mol% or less with respect to the zirconia;

the content of erbium oxide is 1.0 mol% or more and 1.2 mol% or less with respect to the zirconia;

the content of the alumina is 0.23 mass% or more and 0.3 mass% or less, assuming that the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%;

the relative sintering density is more than 99.7%.

In the above structure, it is preferable that, after adjusting the thickness to 5mm and performing mirror polishing, L defined in the L a b color system is more than 75 and not more than 85, a is more than 10 and not more than 20, and b is not less than-1 and not more than 5.

In the structure, preferably, L is more than 77 and less than 83, a is more than 12 and less than 18, and b is more than 0 and less than 3.

When L, a, b specified in the L, a, b color system are within the numerical range, the color is brighter and more vivid, and the color is more balanced.

In the above structure, the three-point bending strength is preferably 1100MPa or more.

When the three-point bending strength is within the above numerical range, the cherry blossom-colored zirconia sintered body can be said to have high strength.

The cherry blossom-color zirconia powder of the present invention comprises:

zirconia including yttria in a range of 0.7 mol% or more and 1.5 mol% or less and including erbium oxide in a range of 0.8 mol% or more and 1.5 mol% or less;

alumina;

zinc oxide; and

silicon dioxide;

the specific surface area is 5m²More than g and 20m²The ratio of the total carbon content to the total carbon content is below g;

the average particle diameter is 0.3 to 0.8 μm.

The cherry blossom-colored zirconia powder of the present invention contains zirconia, yttria, erbium oxide, alumina, zinc oxide, and silica in the above numerical value ranges, and thus, a cherry blossom-colored zirconia sintered body having high mechanical strength can be obtained even at a low molding pressure. In particular, since the specific surface area is 5m²More than g and 20m²Has an average particle diameter of 0.3 to 0.8 μm in terms of a particle size per gram, and therefore, a molded article having a high molding density can be easily obtained, and the sinterability and the sintered density can be easily prevented from being lowered. Further, since erbium oxide, aluminum oxide, zinc oxide and silicon dioxide are contained in the above numerical ranges, the color filter has a bright and vivid color and a good color balance.

As described above, since the cherry-colored zirconia powder of the present invention contains yttrium oxide, erbium oxide, aluminum oxide, zinc oxide, and silicon dioxide within the above numerical ranges, a cherry-colored zirconia sintered body having high strength, bright and vivid color, and good color balance can be obtained even at a low molding pressure. This can also be seen in the examples.

the content of the alumina is more than 0.2 mass% and 0.4 mass% or less, assuming that the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%;

the specific surface area is 5m²More than 15 m/g²The ratio of the carbon atoms to the carbon atoms is less than g.

the average particle diameter is 0.3 to 0.7 μm.

In the structure, it is preferable that the thickness is 0.8t/cm²The three-point bending strength of the sintered body obtained by sintering the molded body at 1350 ℃ for 2 hours under atmospheric pressure is 1100MPa or more.

At 0.8t/cm²When the three-point bending strength of the sintered body obtained by sintering under atmospheric pressure at 1350 ℃ for 2 hours after molding under the molding pressure of (1) is 1100MPa or more, the cherry-colored zirconia sintered body produced using the cherry-colored zirconia powder has high strength even when molded under low pressure.

The method for producing a cherry-colored zirconia powder of the present invention is a method for producing a cherry-colored zirconia powder,

the method for producing cherry blossom-color-based zirconia powder comprises:

step A, mixing alkaline zirconium sulfate, yttrium oxide sol solution and erbium oxide sol solution; and

and a step B of mixing an alkali with the liquid mixture after the step A.

According to the above configuration, in the step a, the dispersion state of the element can be controlled to be uniform by mixing the basic zirconium sulfate, the yttrium oxide sol solution, and the erbium oxide sol solution. Then, by using the thus obtained cherry blossom-colored zirconia powder, a cherry blossom-colored zirconia sintered body having high mechanical strength can be obtained even at a low molding pressure.

Effects of the invention

According to the present invention, a cherry blossom-color-based zirconia sintered body having high strength, a bright and vivid color and a good color balance can be produced even at a low molding pressure. Further, a cherry-colored zirconia powder which can easily produce the sintered cherry-colored zirconia can be provided. Further, a method for producing the cherry blossom-color-based zirconia powder can be provided.

Detailed Description

The following describes embodiments of the present invention. However, the present invention is not limited to these embodiments. In the present specification, zirconia is a general zirconia, and contains 10 mass% or less of an impurity metal compound containing hafnium. In the present specification, expressions such as "including" and "including" include concepts such as "including", "consisting essentially of … …", and "consisting of … …".

[ cherry blossom color-based zirconia powder ]

The cherry blossom-color-based zirconia powder (hereinafter also referred to as zirconia powder) of the present embodiment includes:

alumina;

zinc oxide; and

the amount of silicon dioxide,

the content of the alumina is 0.1 mass% or more and 0.4 mass% or less, where the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%;

a content of the zinc oxide is 0.2 mass% or more and 0.3 mass% or less with a total amount of the zirconium oxide, the yttrium oxide, and the erbium oxide being 100 mass%;

a content of the silica is 0.05 mass% or more and 0.1 mass% or less with a total amount of the zirconia, the yttria, and the erbium oxide being 100 mass%;

the average particle diameter is 0.3 to 0.8 μm.

The zirconia powder contains zirconia. The content of the zirconia is preferably 90 mass% or more, more preferably 92 mass% or more, further preferably 94 mass% or more, and particularly preferably 94.3 mass% or more, when the zirconia powder is 100 mass%. The upper limit of the content of zirconia is not particularly limited, and the content of zirconia is preferably 97.5% by mass or less, more preferably 97.2% by mass or less, still more preferably 97% by mass or less, and particularly preferably 96.9% by mass or less.

The zirconia powder contains 0.7 mol% to 1.5 mol% of yttria with respect to the total mol amount of the zirconia. Yttria is used as the stabilizer. The yttrium oxide may be present in the form of a solid solution with zirconium oxide or in the form of a mixture. From the viewpoint of element dispersibility at the time of sintering, it is preferable that yttria is present in the form of a solid solution with zirconia. That is, the yttria is preferably present in the form of yttria-stabilized zirconia.

The content of the yttrium oxide is preferably 0.8 mol% or more, more preferably 0.85 mol% or more, further preferably 0.9 mol% or more, particularly preferably 0.95 mol% or more, particularly preferably 0.98 mol% or more, and particularly preferably 1.0 mol% or more. The content of the yttrium oxide is preferably 1.4 mol% or less, more preferably 1.3 mol% or less, still more preferably 1.2 mol% or less, particularly preferably 1.1 mol% or less, and particularly preferably 1.05 mol% or less.

The zirconia powder contains erbium oxide in an amount of 0.8 mol% to 1.5 mol% based on the total mol amount of the zirconia. Erbium oxide functions as a colorant of cherry flower color and also functions as a stabilizer. Erbium oxide may be present in the form of a solid solution with zirconium oxide or in the form of a mixture. From the viewpoint of element dispersibility at the time of sintering, it is preferable that erbium oxide is present in the form of a solid solution with zirconia. That is, erbium oxide is preferably present in the form of erbium oxide stabilized zirconia.

In the above-mentioned zirconia powder, it is preferable that yttria and erbium oxide are present in the form of forming a solid solution with zirconia. That is, the yttria and erbium oxide are preferably present in the form of yttria and erbium oxide stabilized zirconia.

The content of erbium oxide is preferably 0.9 mol% or more, more preferably 0.95 mol% or more, still more preferably 1.0 mol% or more, particularly preferably 1.05 mol% or more, and particularly preferably 1.07 mol% or more. The content of erbium oxide is preferably 1.4 mol% or less, more preferably 1.3 mol% or less, still more preferably 1.2 mol% or less, particularly preferably 1.15 mol% or less, and particularly preferably 1.13 mol% or less.

The zirconia powder may also contain other components in place of a portion of the yttria. Examples of other ingredients are: alkaline earth metal oxides such as calcium oxide and magnesium oxide; rare earth oxides such as cerium oxide.

The zirconia powder contains alumina (aluminum oxide). The content of the alumina is 0.1 mass% or more and 0.4 mass% or less, assuming that the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%. Since the content of alumina is within the above numerical range, it functions as a sintering aid. In addition, when only alumina is added as a sintering aid, sintering is not sufficiently performed when the sintering temperature is low (for example, about 1350 ℃). Therefore, in the present embodiment, in order to obtain a sufficient sintered body, silica and zinc oxide are added together with alumina even when sintering is performed at a relatively low temperature.

The content of the alumina is preferably 0.12% by mass or more, more preferably 0.15% by mass or more, further preferably more than 0.20% by mass, particularly preferably 0.22% by mass or more, particularly preferably 0.23% by mass or more, and particularly preferably 0.24% by mass or more. The content of the alumina is preferably 0.35% by mass or less, more preferably 0.3% by mass or less, further preferably 0.28% by mass or less, particularly preferably 0.27% by mass or less, particularly preferably 0.26% by mass or less, and particularly preferably 0.25% by mass or less.

The form of alumina is not particularly limited, but alumina powder is preferred from the viewpoint of operability in producing zirconia powder and reduction of residual impurities.

When the alumina powder is added, the average particle size of the primary particles is not particularly limited, and may be 0.02 to 0.4. mu.m, more preferably 0.05 to 0.3. mu.m, and still more preferably 0.07 to 0.2. mu.m. The average particle diameter of the primary particles of alumina was measured by using a laser diffraction particle diameter distribution measuring apparatus "SALD-2300" (manufactured by Shimadzu corporation).

The zirconia powder contains zinc oxide. The content of the zinc oxide is 0.2 to 0.3 mass% based on 100 mass% of the total amount of the zirconium oxide, yttrium oxide, and erbium oxide. When the zinc oxide and the silicon dioxide are added together, the zinc oxide and the silicon dioxide play a role of a sintering aid, increase the whiteness and improve the brightness. In the case where no silica is added, the relative sintered density does not increase even if zinc oxide is added. The specific reason is not clear, but the present inventors speculate that silica and zinc oxide form a compound and function as a sintering aid. That is, when silica and zinc oxide are added simultaneously, they function better as sintering aids, and can increase whiteness and brightness while promoting sintering. Since the zirconia powder of the present embodiment contains silica and zinc oxide in addition to alumina, sintering is promoted even at a low sintering temperature of 1350 ℃. The zirconia powder can sufficiently promote sintering even at a low sintering temperature of 1350 ℃, but it is needless to say that the zirconia powder can be sintered at a temperature of 1350 ℃ or higher to obtain a sintered body.

The content of the zinc oxide is preferably 0.12% by mass or more, more preferably 0.15% by mass or more, further preferably 0.20% by mass or more, particularly preferably 0.22% by mass or more, and particularly preferably 0.24% by mass or more. The content of the zinc oxide is preferably 0.35% by mass or less, more preferably 0.3% by mass or less, further preferably 0.28% by mass or less, particularly preferably 0.27% by mass or less, particularly preferably 0.26% by mass or less, and particularly preferably 0.25% by mass or less.

The form of zinc oxide is not particularly limited, but from the viewpoint of workability in the production of the zirconia powder and reduction of residual impurities, zinc oxide powder is preferred.

When the zinc oxide powder is added, the average particle size of the primary particles is not particularly limited, and may be 0.02 to 20 μm, more preferably 0.1 to 10 μm, and still more preferably 0.05 to 7 μm. From the viewpoint of sinterability and color unevenness of the sintered body, the particle diameter is preferably substantially the same as the particle diameter of zirconia. The average particle diameter of the primary particles of zinc oxide was measured by using a laser diffraction particle diameter distribution measuring apparatus "SALD-2300" (manufactured by Shimadzu corporation).

The zirconia powder contains silica. The content of the silica is 0.05 mass% or more and 0.1 mass% or less, where the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%. When added together with zinc oxide, silica functions as a sintering aid, and increases whiteness and brightness. In the case where zinc oxide is not added, the relative sintered density does not increase even if silica is added. As described above, when silica and zinc oxide are added simultaneously, they function better as sintering aids, and can increase whiteness and brightness while promoting sintering.

The content of the silica is preferably 0.055% by mass or more, more preferably 0.06% by mass or more, further preferably 0.065% by mass or more, and particularly preferably 0.067% by mass or more. The content of the silica is preferably 0.09% by mass or less, more preferably 0.08% by mass or less, still more preferably 0.075% by mass or less, and particularly preferably 0.073% by mass or less.

The form of silica is not particularly limited, but silica powder is preferable from the viewpoint of operability in preparing zirconia powder and reduction of residual impurities.

When the silica powder is added, the average particle size of the primary particles is not particularly limited, but may be 0.02 to 20 μm, more preferably 0.1 to 10 μm, and still more preferably 0.05 to 7 μm. From the viewpoint of sinterability and color unevenness of the sintered body, the particle diameter is preferably substantially the same as the particle diameter of zirconia. The average particle diameter of the primary particles of silica is a value measured by using a laser diffraction particle diameter distribution measuring apparatus "SALD-2300" (manufactured by Shimadzu corporation).

The zirconia powder has an average particle diameter of 0.3 to 0.8 [ mu ] m. Since the average particle diameter of the zirconia powder is within the above range, a molded body having a high molded density can be easily obtained, and the sinterability and the sintered density can be easily suppressed from decreasing. Further, since the average particle diameter of the zirconia powder is within the above range, it is not necessary to extend the pulverizing time in the pulverizing step. Further, since the zirconia powder has an average particle size of 0.8 μm or less, the monoclinic phase in the powder is not excessive, and therefore, a sintered body having a high sintering density can be easily obtained. The average particle diameter of the zirconia powder is preferably 0.35 μm or more, and more preferably 0.4 μm or more. The average particle diameter of the zirconia powder is preferably 0.75 μm or less, and more preferably 0.7 μm or less.

The average particle diameter of the zirconia powder was measured by using a laser diffraction particle size distribution measuring apparatus "SALD-2300" (manufactured by Shimadzu corporation). See the methods described in the examples. The average particle diameter described in the present specification is a value measured on a volume basis.

The zirconia powder had a specific surface area of 5m²More than g and 20m²The ratio of the carbon atoms to the carbon atoms is less than g. The specific surface area of the zirconia powder is 5m²More than g and 20m²Less than g, thereforeA molded body having a high molding density can be easily obtained, and the reduction of sinterability and sintered density can be easily suppressed. The specific surface area of the zirconia powder is preferably 6m²A value of at least one of,/g, more preferably 6.5m²A total of 7m or more, preferably²More than g. The specific surface area of the zirconia powder is preferably 18m²A ratio of 15m or less per gram²A total of 13m or less, preferably²The ratio of the carbon atoms to the carbon atoms is less than g.

In the present specification, the specific surface area of the zirconia powder refers to BET specific surface area, and is a value measured using a specific surface area meter "Macsorb" manufactured by Mountech.

The zirconia powder is 0.8t/cm²The three-point bending strength of the sintered body sintered under the conditions of atmospheric pressure, 1350 ℃ and 2 hours after molding under the molding pressure of (3) is preferably 1100MPa or more, more preferably 1150MPa or more, still more preferably 1200MPa or more, and particularly preferably 1350MPa or more. The three-point bending strength is preferably as large as possible, and may be, for example, 1500MPa or less, 1450MPa or less, 1400MPa or less, or the like. When the three-point bending strength is 1100MPa or more, a sintered body produced using the zirconia powder has high strength even when molded under low pressure.

The details of the method for measuring the three-point bending strength described above are shown in examples.

In addition, "at 0.8t/cm²The conditions of sintering under the conditions of 1350 ℃ for 2 hours under atmospheric pressure after molding under the molding pressure of (1) are molding and sintering conditions for evaluating the physical properties of the zirconia powder, assuming production conditions of sintering after low-pressure molding; it is not intended that the zirconia powder be molded and sintered under the above conditions when the zirconia sintered body is produced using the zirconia powder.

As described above, according to the zirconia powder of the present embodiment, since yttria, erbium oxide, alumina, zinc oxide, and silica are contained in the above numerical value range, a cherry-colored zirconia sintered body having high mechanical strength can be obtained even at a low molding pressure. In particular, since the specific surface area is 5m²More than g and 20m²A ratio ofSince the average particle diameter is 0.3 μm or more and 0.8 μm or less, a molded body having a high molding density can be easily obtained, and the sinterability and the sintered density can be easily suppressed from decreasing. Further, since erbium oxide, aluminum oxide, zinc oxide and silicon dioxide are contained in the above numerical range, the color filter has a bright and vivid color and a good color balance.

As described above, the zirconia powder of the present embodiment contains yttria, erbium oxide, alumina, zinc oxide, and silica in the above numerical value range, and therefore, a cherry-colored zirconia sintered body having high strength, bright and vivid color, and good color balance can be obtained even at a low molding pressure. This can also be seen in the examples.

The zirconia powder of the present embodiment is explained above.

[ method for producing cherry blossom color-based zirconia powder ]

An example of a method for producing cherry blossom-color-based zirconia powder is described below. However, the method for producing the cherry blossom-colored zirconia powder of the present invention is not limited to the following examples.

The method for producing a cherry blossom-color-based zirconia powder according to the present embodiment includes:

and a step B of mixing a base after the step A.

In the method for producing the cherry blossom-colored zirconia powder of the present embodiment, first, an alkaline zirconium sulfate, an yttria sol solution, and an erbium oxide sol solution are mixed (step a). In the step a, since the basic zirconium sulfate, the yttrium oxide sol solution, and the erbium oxide sol solution are mixed, the dispersion state of the elements can be controlled to be uniform.

The basic zirconium sulfate is not particularly limited, and examples thereof include ZrOSO₄·ZrO₂、5ZrO₂·3SO₃、7ZrO₂·3SO₃Etc. are disclosed. Hydrates of these compounds may be usedOne or more than two of the above-mentioned raw materials are used.

Generally, these basic salts are obtained as aggregates of microparticles having a particle size of several tens of angstroms (i.e., aggregated particles having a particle size of 0.1 to tens of μm) which have a low solubility and are obtained by optical measurement, and can be obtained by a known production method. Further, commercially available products may be used. For example, "Gmelin Handbuch, TEIL 42; basic salts described in Zirkonitum (ISBN 3-540-.

As shown in this embodiment, the yttrium oxide raw material is preferably yttrium oxide sol. The yttria sol may be obtained by a known production method or may be a commercially available product.

The average particle size of the yttrium oxide sol is preferably 10 to 150nm, more preferably 15 to 120nm, still more preferably 20 to 100nm, and particularly preferably 30 to 80 nm. When the average particle diameter of the yttria sol is 10nm or more, the dispersion degree of yttria in zirconia is preferable. The average particle diameter of the yttria sol is a value obtained by Zetasizer Nano ZS (manufactured by spectroris, ltd.).

The concentration of the yttria sol solution is not particularly limited, but is preferably 1 to 30% by mass, and more preferably 3 to 25% by mass. As a method for producing the yttria sol, for example, a method disclosed in japanese patent No. 4518844 and the like can be cited.

The amount of yttria sol added to the cherry blossom-color zirconia powder is 0.07 mol% or more and 1.5 mol% or less in terms of yttria. The addition amount of the yttria sol is preferably 0.8 mol% or more, more preferably 0.85 mol% or more, further preferably 0.9 mol% or more, particularly preferably 0.95 mol% or more, and particularly preferably 0.98 mol% or more in terms of yttria. The addition amount of the yttria sol is preferably 1.5 mol% or less, more preferably 1.4 mol% or less, further preferably 1.3 mol% or less, particularly preferably 1.2 mol% or less, particularly preferably 1.1 mol% or less, and particularly preferably 1.05 mol% or less in terms of yttria.

As described in this embodiment, erbium oxide sol is preferable as a raw material of erbium oxide. The erbium oxide sol may be a commercially available product or a product obtained by a known production method.

The erbium oxide sol preferably has an average particle diameter of 10 to 150nm, more preferably 15 to 120nm, still more preferably 20 to 100nm, and particularly preferably 30 to 80 nm. When the average particle diameter of the erbium oxide sol is 10nm or more, the dispersion degree of erbium oxide in zirconia is preferable. The average particle diameter of the erbium oxide sol is a value obtained by Zetasizer Nano ZS (manufactured by spectroris, ltd.).

The concentration of the erbium oxide sol solution is not particularly limited, but is preferably 1 to 30 mass%, more preferably 3 to 25 mass%. Examples of the method for producing the erbium oxide sol include methods disclosed in japanese patent No. 4488831 and the like.

The amount of erbium oxide sol added to the cherry blossom-color-based zirconia powder is 0.8 mol% or more and 1.5 mol% or less in terms of erbium oxide. The amount of the erbium oxide sol to be added is preferably 0.9 mol% or more, more preferably 0.95 mol% or more, further preferably 1.0 mol% or more, particularly preferably 1.05 mol% or more, and particularly preferably 1.07 mol% or more in terms of erbium oxide. The amount of erbium oxide sol added is preferably 1.5 mol% or less, more preferably 1.4 mol% or less, further preferably 1.3 mol% or less, particularly preferably 1.2 mol% or less, particularly preferably 1.15 mol% or less, and particularly preferably 1.13 mol% or less in terms of erbium oxide.

The solvent used when mixing the basic zirconium sulfate, yttrium oxide sol solution and erbium oxide sol solution is not particularly limited as long as it can disperse the basic zirconium sulfate, yttrium oxide sol and erbium oxide sol, but water (ion-exchanged water, etc.), alcohols (methanol, ethanol, etc.), and the like can be generally used as the polar solvent. From the viewpoint of cost reduction, the most preferable solvent is water. The concentration of the mixed solution obtained by mixing the basic zirconium sulfate, yttrium oxide sol solution and erbium oxide sol solution may be appropriately changed depending on the composition ratio of the composite oxide, but is usually about 1 to 25 mass%, and preferably 10 to 20 mass%.

The mixing ratio of the basic zirconium sulfate, the yttrium oxide sol solution, and the erbium oxide sol solution can be determined by appropriately adjusting the solution concentration and the like so as to have the above composition ratio.

The temperature of the mixed solution is usually 80 ℃ or lower, preferably 20 to 50 ℃.

The order of mixing the yttria sol solution and the erbium oxide sol solution in the basic zirconium sulfate is not particularly limited, and it is preferable to mix either one of the yttria sol solution and the erbium oxide sol solution in the basic zirconium sulfate and then mix the other. Alternatively, the yttria sol solution and the erbium oxide sol solution may be mixed together in the basic zirconium sulfate.

The mixing method is preferably to drop the yttria sol solution and the erbium oxide sol solution little by little into the basic zirconium sulfate. The dropping time is preferably relatively long. Specifically, the dropping time is preferably 1 to 10 hours, more preferably 2 to 5 hours, and still more preferably 2.5 to 4 hours. The above-mentioned dropping time means a period from the start of dropping to the end of dropping. The dropping time is a time for dropping either the yttria sol solution or the erbium oxide sol solution. That is, in the case where either one of the yttria sol solution and the erbium oxide sol solution is mixed in the basic zirconium sulfate and then the other is mixed, the time until the completion of the process a is the sum of the dropping time of the yttria sol solution and the dropping time of the erbium oxide sol solution. In the above mixing, it is preferable to perform stirring in addition to dropping. When the dropping time is 1 hour or more, the segregation of yttrium oxide and erbium oxide can be further suppressed. In addition, if the dropping time is 10 hours or less, the manufacturing cost can be controlled.

< Process B >

After the step a, an alkali is mixed into the mixed solution (step B). Thereby, a precipitate (zirconium hydroxide) was generated.

The alkali is not particularly limited, and for example, a known alkali agent such as sodium hydroxide, potassium hydroxide, sodium carbonate, ammonium carbonate, or ammonia can be used. In particular, strong bases such as sodium hydroxide and potassium hydroxide are preferably used as the base. In addition, the alkali is preferably mixed in the form of an aqueous solution. In this case, the concentration of the aqueous solution is not particularly limited as long as the pH can be adjusted, and is usually about 5 to 50% by mass, preferably 20 to 25% by mass.

After mixing the alkali, solid-liquid separation may be performed as necessary, and the obtained zirconium hydroxide may be washed with water. The solid-liquid separation method may be a general method such as centrifugation. The zirconium hydroxide after the water washing treatment is dispersed in a dispersion medium such as water, so that zirconium hydroxide slurry can be obtained.

Then, the zirconium hydroxide is heated in an atmosphere at a temperature of 1000 to 1200 ℃ (calcination temperature). The zirconium hydroxide is calcined by this heat treatment to form zirconium oxide. If necessary, the resultant may be subjected to a pulverization treatment, a classification treatment, or the like. When the calcination temperature is within the above range, the pulverization, molding and sintering can be easily controlled.

The calcination temperature is preferably 1040-1180 ℃. The atmosphere at the time of calcination may be in the atmosphere or in an oxidizing atmosphere.

The rate of temperature increase from room temperature (25 ℃) to the calcination temperature is not particularly limited, and may be 50 to 200 ℃/hr, and more preferably 100 to 150 ℃/hr.

The method of pulverization in the above-mentioned pulverization treatment is not particularly limited, and examples thereof include a method of pulverization by a commercially available pulverizer such as a planetary mill, a ball mill, or a jet mill.

Then, alumina, zinc oxide and silica were mixed in the obtained zirconia. The mixing method of zirconia, alumina, zinc oxide and silica is not particularly limited. The zirconia, alumina, zinc oxide and silica may be mixed at the same time, or the zinc oxide and silica may be mixed after the zirconia and alumina are mixed. In the case of using alumina powder, alumina may be added to the zirconium hydroxide slurry before calcination.

The amount of the alumina is 0.1 to 0.4 mass% inclusive, based on 100 mass% of the total amount of the zirconia, the yttria, and the erbium oxide; a content of the zinc oxide is 0.2 mass% or more and 0.3 mass% or less with a total amount of the zirconium oxide, the yttrium oxide, and the erbium oxide being 100 mass%; the content of the silica is 0.05 mass% or more and 0.1 mass% or less, where the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%.

The amount of the alumina is preferably 0.12% by mass or more, more preferably 0.15% by mass or more, further preferably more than 0.20% by mass, particularly preferably 0.22% by mass or more, particularly preferably 0.23% by mass or more, and particularly preferably 0.24% by mass or more, assuming that the total amount of the zirconia, the yttria, and the erbium oxide is 100% by mass. The amount of the alumina is preferably 0.35% by mass or less, more preferably 0.3% by mass or less, further preferably 0.28% by mass or less, particularly preferably 0.27% by mass or less, particularly preferably 0.26% by mass or less, and particularly preferably 0.25% by mass or less, assuming that the total amount of the zirconia, the yttria, and the erbium oxide is 100% by mass.

The amount of zinc oxide to be mixed is preferably 0.21 mass% or more, more preferably 0.22 mass% or more, further preferably 0.23 mass% or more, particularly preferably 0.24 mass% or more, and particularly preferably 0.245 mass% or more, assuming that the total amount of the zirconium oxide, yttrium oxide, and erbium oxide is 100 mass%. The amount of zinc oxide to be mixed is preferably 0.35% by mass or less, more preferably 0.3% by mass or less, still more preferably 0.28% by mass or less, particularly preferably 0.27% by mass or less, particularly preferably 0.26% by mass or less, and particularly preferably 0.25% by mass or less, assuming that the total amount of the zirconium oxide, the yttrium oxide, and the erbium oxide is 100% by mass.

The amount of the silica to be mixed is preferably 0.055% by mass or more, more preferably 0.06% by mass or more, further preferably 0.065% by mass or more, and particularly preferably 0.067% by mass or more, assuming that the total amount of the zirconia, the yttria, and the erbium oxide is 100% by mass. The amount of the silica to be mixed is preferably 0.1% by mass or less, more preferably 0.09% by mass or less, further preferably 0.08% by mass or less, particularly preferably 0.075% by mass or less, and particularly preferably 0.073% by mass or less, with the total amount of the zirconia, the yttria, and the erbium oxide being 100% by mass.

The mixing can be carried out using a commercially available apparatus. For example, a V-type mixer, various mixers, and the like can be used. After mixing, a granular powder may be formed by spray drying treatment or the like as necessary.

In the method for producing the cherry blossom-color-based zirconia powder of the present embodiment, the zirconia powder obtained may be pulverized and slurried as necessary. In this case, a binder may be added to improve moldability. If the slurry is not formed, the binder and the zirconia powder can be uniformly mixed by a kneader.

The binder is preferably an organic binder. Since the organic binder is easily removed from the molded body in a heating furnace in an oxidizing atmosphere, a degreased body can be obtained, and thus impurities are not likely to remain in the sintered body finally.

Examples of the organic binder include alcohols. The organic binder may be a binder that dissolves a mixed liquid of 2 or more selected from the group consisting of alcohol, water, aliphatic ketone, and aromatic hydrocarbon. Specifically, for example, one or more selected from the group consisting of polyethylene glycol, ethylene glycol fatty acid ester, glycerin fatty acid ester, polyvinyl butyral, polyvinyl methyl ether, polyvinyl ethyl ether, and vinyl propionate may be cited. The organic binder may include one or more thermoplastic resins insoluble in alcohol or the above-mentioned mixed solution.

After the organic binder and the like are mixed, the target zirconia powder can be obtained by treatment such as drying and pulverization using a known method.

The method for producing the zirconia powder of the present embodiment is explained above.

[ cherry blossom color-based zirconia sintered body ]

The cherry blossom-colored zirconia sintered body (hereinafter, also referred to as zirconia sintered body) of the present embodiment includes:

zirconia, yttria, erbium oxide, alumina, zinc oxide, and silica;

the content of erbium oxide is 0.7 mol% or more and 1.5 mol% or less with respect to the zirconium oxide;

the relative sintering density is more than 99.5 percent.

The zirconia sintered body contains zirconia. The content of the zirconia is preferably 90 mass% or more, more preferably 92 mass% or more, further preferably 94 mass% or more, and particularly preferably 94.3 mass% or more, assuming that the zirconia sintered body is 100 mass%. The upper limit of the content of zirconia is not particularly limited, and the content of zirconia is preferably 97.5% by mass or less, more preferably 97.2% by mass or less, still more preferably 97% by mass or less, and particularly preferably 96.9% by mass or less.

The zirconia sintered body contains 0.7 mol% to 1.5 mol% of yttria with respect to the total mol amount of zirconia.

The zirconia sintered body contains erbium oxide in an amount of 0.8 mol% to 1.5 mol% based on the total mol amount of the zirconia.

The zirconia sintered body contains alumina (aluminum oxide). The content of the alumina is 0.1 mass% or more and 0.4 mass% or less, assuming that the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%.

The zirconia sintered body contains zinc oxide. The content of the zinc oxide is 0.2 to 0.3 mass% based on 100 mass% of the total amount of the zirconium oxide, yttrium oxide, and erbium oxide.

The zirconia sintered body contains silica. The content of the silica is 0.05 mass% or more and 0.1 mass% or less, where the total amount of the zirconia, the yttria, and the erbium oxide is 100 mass%.

The zirconia sintered body has a relative sintered density of 99.5% or more. The relative sintered density is more preferably 99.6% or more, still more preferably 99.7% or more, and particularly preferably 99.8% or more. Since the relative sintered density is 99.5% or more, the zirconia sintered body has high strength.

The relative sintered density mentioned above means a relative sintered density represented by the following formula (1).

Relative sintered density (%) (sintered density/theoretical sintered density) × 100 (1)

Wherein the theoretical sintered density (denoted as ρ)₀) Is a value calculated by the following formula (2-1). Here, approximation is performed so that the ion radius of Er approaches the ion radius of Y, and the like.

ρ₀＝100/[(Y/3.987)+(100-Y)/ρz] (2-1)

Where ρ z is a value calculated by the following formula (2-2).

Rho z ═ molecular weight of [124.25(100-X) + [ stabilizer]×X]/[150.5(100+X)A²C](2-2)

Wherein Y in the stabilizer is used as the molecular weight of the stabilizer₂O₃Use of 225.81, Er₂O₃Using 382.52, the average molecular weight was calculated from each mixing ratio and used as the molecular weight of the stabilizer.

In addition, X and Y are a stabilizer concentration (mol%) and an alumina concentration (mass%), respectively. In addition, A and C are values calculated by the following formulas (2-3) and (2-4), respectively.

A＝0.5080+0.06980X/(100+X) (2-3)

C＝0.5195-0.06180X/(100+X) (2-4)

In formula (1), the theoretical sintered density varies depending on the composition of the powder. For example, in the case where the content of yttria is 1 mol% and the content of erbium oxide is 1 mol%, the theoretical sintered density of yttria-containing zirconia is 6.193g/cm³(in Al)₂O₃When it is 0 mass%). Even when zinc oxide or silica is added, the theoretical density can be calculated by the same calculation method as that for the addition of alumina. Sintered density can be measured by archimedes' method. See the methods described in the examples.

In the above zirconia sintered body, L defined in the color system is preferably more than 75 and 85 or less. L is more preferably 76 or more, still more preferably 77 or more, particularly preferably 78 or more, and particularly preferably 79 or more. L is more preferably 84 or less, still more preferably 83 or less, particularly preferably 82 or less, and particularly preferably 81 or less.

In the above zirconia sintered body, a defined in the color system is preferably more than 10 and 20 or less. A is more preferably 11 or more, further preferably 12 or more, particularly preferably 13 or more, and particularly preferably 14 or more. A is more preferably 19 or less, still more preferably 18 or less, particularly preferably 17 or less, and particularly preferably 16 or less.

In the above zirconia sintered body, b defined in the color system is preferably-1 to 5. B is more preferably 0.5 or more, still more preferably 1 or more, particularly preferably 1.5 or more, and particularly preferably 2 or more. B is preferably 4 or less, more preferably 3.5 or less, particularly preferably 3 or less, and particularly preferably 2.5 or less.

When L, a, b specified in the aforementioned L × a × b color system are within the aforementioned numerical value range, a cherry blossom color system having a brighter and more uniform color is formed. The aforementioned L a b is measured after the zirconia sintered body was mirror-polished. See the methods described in the examples for more specific methods of measurement. In addition, the L × a × b color system is a color space recommended by the international commission on illumination (CIE) in 1976, and means a color space called CIE1976(L × a × b) color system. In addition, the L × a × b color system is defined in japanese industrial standards as JIS Z8729. In the present specification, the values of L, a, and b (measurement of color tone) are measured after adjusting the zirconia sintered body to a thickness of 5mm and mirror polishing using diamond gypsum containing diamond abrasive grains having a grain size of 3 μm or less.

The three-point bending strength of the zirconia sintered body is preferably 1100MPa or more, more preferably 1150MPa or more, still more preferably 1200MPa or more, and particularly preferably 1350MPa or more. The three-point bending strength is preferably as large as possible, and may be, for example, 1500MPa or less, 1450MPa or less, 1400MPa or less, or the like. The three-point bending strength is high when 1100MPa or more.

The method for measuring the three-point bending strength is described in examples.

As described above, according to the zirconia sintered body of the present embodiment, since yttria, erbium oxide, alumina, zinc oxide, and silica are contained within the above numerical value range, it has high strength even when manufactured under a low molding pressure. Specifically, the zirconia sintered body of the present embodiment has a high strength because the relative sintered density is 99.5% or more. Further, since erbium oxide, aluminum oxide, zinc oxide and silicon dioxide are contained within the above numerical ranges, bright and vivid color tone is obtained and color balance is good.

As described above, since the zirconia sintered body of the present embodiment contains yttria, erbium oxide, alumina, zinc oxide, and silica within the above numerical value ranges, it has high strength, bright and vivid color tone, and good color balance even when produced under a low molding pressure. This can also be seen in the examples.

The zirconia sintered body can be produced by a method for producing a cherry-color zirconia sintered body described below. However, the method for producing the zirconia sintered body is not limited to this example.

The zirconia sintered body of the present embodiment is explained above.

[ method for producing cherry-color-based zirconia sintered body ]

Hereinafter, one example of a method for producing a zirconia sintered body will be described, but the method is not limited to the following example.

The method for producing a zirconia sintered body of the present embodiment includes:

step X of pulverizing the above zirconia powder at 0.7t/cm²Above and 0.9t/cm²Molding under the following molding pressure to obtain a molded body; and

and a step Y of sintering the molded article under conditions of 1300 ℃ to 1550 ℃ and 1 hour to 10 hours after the step X.

< Process X >

In the method for producing a zirconia sintered body according to the present embodiment, first, the zirconia powder is made to be 0.7t/cm²Above and 0.9t/cm²The molding was carried out under the following molding pressure to obtain a molded article (step X). The molding pressure is preferably 0.75t/cm²Above and 0.9t/cm²Hereinafter, more preferably 0.75t/cm²Above and 0.85t/cm²The following.

When the zirconia powder is molded, a commercially available mold molding machine and Cold Isostatic Pressing (CIP) method can be used. Alternatively, the present molding may be performed by extrusion molding such as CIP after the zirconia powder is temporarily molded by a die-molding machine. In the past, the production of a molded body of zirconia powder was carried out under high pressure, but in the present embodiment, it was 0.7t/cm²Above and 0.9t/cm²The molded article was produced under such a low molding pressure as follows. In the present embodiment, by using the zirconia powder, a sintered body having high strength can be obtained even when a molded body is produced at such a low molding pressure.

< Process Y >

After the step X, the molded article is sintered under conditions of 1300 ℃ to 1550 ℃ and 1 hour to 10 hours inclusive (step Y). Thus, the zirconia sintered body of the present embodiment is obtained.

The sintering temperature at the time of sintering is preferably 1350 ℃ or more and 1500 ℃ or less, more preferably 1400 ℃ or more and 1490 ℃ or less, and still more preferably 1420 ℃ or more and 1480 ℃ or less.

The holding time at the time of sintering is preferably 1 hour to 5 hours, more preferably 2 hours to 4 hours, and further preferably 2 hours to 3 hours. The atmosphere at the time of sintering may be in the atmosphere or in an oxidizing atmosphere.

The method for producing the zirconia sintered body of the present embodiment is explained above.

[ examples ] A method for producing a compound

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples as long as the invention does not exceed the gist thereof. The zirconia powders obtained in examples and comparative examples contained 1.3 to 2.5 mass% of hafnium oxide as an inevitable impurity (calculated by the following formula (X)) relative to zirconia.

< formula (X) >

([ mass of hafnium oxide ]/([ mass of zirconium oxide ] + [ mass of hafnium oxide ])). times.100 (%)

Production of zirconia powder

(example 1)

Basic zirconium sulfate (containing 100g of zirconia) was dispersed in 1000g of water to form a basic zirconium sulfate slurry. Further, an yttria sol solution having a concentration of 5% by mol based on zirconia was measured (average particle diameter of yttria sol: 30nm, manufactured by first rare element chemical Co., Ltd.). Further, an erbium oxide sol solution having a concentration of 5% by mol with respect to zirconia was measured (average particle diameter of erbium oxide sol: 40nm, manufactured by first rare element chemical industry Co., Ltd.).

The average particle diameters of the yttria sol and the erbium oxide sol were values obtained by using Zetasizer Nano ZS (manufactured by Spectris corporation). The details are as follows.

The model is as follows: zetasizer Nano ZS (manufactured by Spectris, Ltd.)

And (3) measuring the concentration: calculated by metal oxide is 30 percent

Measuring the temperature: 25 deg.C

Scattering angle: 173 degree

While stirring the basic zirconium sulfate slurry, the weighed yttrium oxide sol solution was first dropped and mixed within 3 hours. The measured erbium oxide sol solution was then dropped and mixed within 3 hours. Thereby obtaining a mixed solution.

Then, a 25 mass% aqueous sodium hydroxide solution was added to the mixture until the pH reached 13.5, to obtain a precipitate.

Then, the precipitate is subjected to solid-liquid separation by decantation or the like and washed, and the process is repeated several times until the impurities are extremely reduced to obtain a predetermined solid content.

Then, the recovered solid component was calcined at 1100 ℃ for 2 hours in the air to obtain zirconia (zirconium oxide). The temperature rise rate was 100 ℃ per hour.

To the obtained zirconia, 0.25 mass% of alumina powder having an average particle size of primary particles of 0.1 μm was added to zirconium oxide, 0.25 mass% of zinc oxide was added to zirconium oxide, and 0.07 mass% of silica powder was added to zirconium oxide, and the mixture was pulverized and mixed in a wet ball mill using water as a dispersion medium for 30 hours. The resulting slurry was dried at 120 ℃ to a constant amount to obtain cherry blossom-colored zirconia powder of example 1.

(examples 2 to 5 and comparative examples 1 to 3)

Zirconia powders of examples 2 to 5 and comparative examples 1 to 3 were obtained in the same manner as in example 1, except that the content of yttria, the content of erbium oxide, the content of alumina, the content of zinc oxide, and the content of silica were changed as shown in table 1.

[ measurement of composition of zirconia powder ]

The compositions (in terms of oxides) of the zirconia powders of examples and comparative examples were analyzed by ICP-AES ("ULTIMA-2," manufactured by HORIBA). As shown in table 1.

[ average particle diameter of zirconia powder ]

The average particle diameter of the zirconia powders obtained in examples and comparative examples was measured by a laser diffraction particle diameter distribution measuring apparatus "SALD-2300" (manufactured by Shimadzu corporation). More specifically, 0.15g of the sample and 40ml of a 0.2% aqueous solution of sodium hexametaphosphate were placed in a 50ml beaker, dispersed in a desktop ultrasonic cleaner "W-113" (manufactured by Sudoelectronics Co., Ltd.) for 2 minutes, and then placed in a laser diffraction type particle size distribution measuring apparatus ("SALD-2300" manufactured by Shimadzu corporation)) for measurement. The results are shown in Table 1.

[ measurement of specific surface area of zirconia powder ]

The specific surface areas of the zirconia powders obtained in examples and comparative examples were measured by the BET method using a specific surface area meter ("Macsorb", manufactured by Mountec corporation). The results are shown in Table 1.

[ three-point bending Strength of zirconia sintered body ]

The zirconia powders of the examples and comparative examples were set at 0.8t/cm²Molding under the molding pressure of (1). Then, the mixture was sintered at 1350 ℃ for 2 hours under atmospheric pressure (1 atm). Thereafter, the three-point bending strength of the obtained sintered body was measured in accordance with the three-point bending strength of JIS R1601. The results are shown in Table 1.

[ at 0.8t/cm²The relative sintered density of the sintered body after molding under the molding pressure of (3), and sintering the sintered body at 1350 ℃ for 2 hours under atmospheric pressure]

The zirconia powders of the examples and comparative examples were set at 0.8t/cm²Molding under the molding pressure of (1). Then, the mixture was sintered at 1350 ℃ for 2 hours under atmospheric pressure (1 atm). Then, the relative sintering density of the obtained sintered body was obtained by the formula (1).

Wherein the theoretical sintered density(note as ρ₀) Is a value calculated by the following formula (2-1). Here, approximation is performed so that the ion radius of Er approaches the ion radius of Y, and the like.

ρ₀＝100/[(Y/3.987)+(100-Y)/ρz] (2-1)

Where ρ z is a value calculated by the following formula (2-2).

Wherein, as the molecular weight of the stabilizer, in the stabilizer, Y₂O₃Use of 225.81, Er₂O₃Using 382.52, the average molecular weight was calculated from each mixing ratio and used as the molecular weight of the stabilizer.

A＝0.5080+0.06980X/(100+X) (2-3)

C＝0.5195-0.06180X/(100+X) (2-4)

In formula (1), the theoretical sintered density varies depending on the composition of the powder. For example, in the case where the content of yttria is 1 mol% and the content of erbium oxide is 1 mol%, the theoretical sintered density of yttria-containing zirconia is 6.193g/cm³(in Al)₂O₃When it is 0 mass%). Even when zinc oxide or silica is added, the theoretical density can be calculated by the same calculation method as that for the addition of alumina. The sintered density was measured by the archimedes method.

[ color tone of sintered body ]

The zirconia powders of the examples and comparative examples were set at 0.8t/cm²Molding under the molding pressure of (1). Then, the mixture was sintered at 1350 ℃ for 2 hours under atmospheric pressure (1 atm). The obtained zirconia sintered body was adjusted to a thickness of 5mm, and then mirror-polished using an automatic polisher ("Ecome 250" manufactured by BUEHLER). In the finish of mirror polishing, diamond gypsum containing diamond abrasive grains having a grain size of 3 μm was used. Thereafter, a color difference meter (trade name: CM-3500d, Konic) was useda manufactured by Minolta corporation) was measured. The results are shown in Table 1.

TABLE 1

Since the cherry-colored zirconia sintered bodies obtained from the zirconia powders of examples 1 to 5 contained predetermined amounts of zirconia, yttria, erbium oxide, alumina, zinc oxide, and silica, they had high strength even when produced under low molding pressure, had bright and vivid color, and had good color balance.

On the other hand, the zirconia powder of comparative example 1 did not contain zinc oxide. The zirconia powder of comparative example 2 did not contain silica. The zirconia powder of comparative example 3 did not include zinc oxide and silica. The zirconia sintered bodies obtained from the zirconia powders of comparative examples 1 to 3 were not sufficiently sintered because they contained no zinc oxide and/or silica. As a result, the zirconia sintered bodies obtained from the zirconia powders of comparative examples 1 to 3 had poor three-point bending strength. In addition, the zirconia sintered bodies obtained from the zirconia powders of comparative examples 1 to 3 had low light transmittance (high L).

Claims

1. A cherry blossom-color-based zirconia sintered body, comprising:

zirconia, yttria, erbium oxide, alumina, zinc oxide, and silica;

the relative sintering density is more than 99.5 percent.

2. The cherry-colored zirconia sintered body according to claim 1,

the content of the yttrium oxide is 0.9 mol% or more and 1.3 mol% or less with respect to the zirconium oxide;

3. The cherry-colored zirconia sintered body according to claim 2,

the content of the yttrium oxide is 1.0 mol% or more and 1.2 mol% or less with respect to the zirconium oxide;

the relative sintering density is more than 99.7%.

4. The cherry-colored zirconia sintered body according to claim 1,

after adjusting the thickness to 5mm and performing mirror polishing, L specified in the color system is more than 75 and less than 85, a is more than 10 and less than 20, and b is more than-1 and less than 5.

5. The cherry-colored zirconia sintered body according to claim 4,

l is more than 77 and less than 83, a is more than 12 and less than 18, b is more than 0 and less than 3.

6. The cherry-colored zirconia sintered body according to any one of claims 1 to 5,

the three-point bending strength is over 1100 MPa.

7. A cherry blossom-color-based zirconia powder, comprising:

alumina;

zinc oxide; and

silicon dioxide;

the average particle diameter is 0.3 to 0.8 μm.

8. The cherry blossom-colored zirconia powder according to claim 7,

9. The cherry blossom-colored zirconia powder according to claim 8,

the average particle diameter is 0.3 to 0.7 μm.

10. The cherry blossom-colored zirconia powder according to any one of claims 7 to 9,

at 0.8t/cm²The three-point bending strength of a sintered body obtained by sintering the molded body at 1350 ℃ for 2 hours under atmospheric pressure after molding under the molding pressure of (2) is 1100MPa or more.

11. A method for producing a cherry blossom-colored zirconia powder according to any one of claims 7 to 10, comprising:

and step B, mixing alkali in the mixed solution after the step A.